I gave up TV and computer games about two years ago. The first was easy, the second was harder. The way to do it is just to have a lot of creative projects on the go. In my case it was a start-up and a band, but it could be anything. As soon as you start creating, you get way more sucked in than you ever do with TV.

The only tricky part is finding something to keep your mind occupied when you're eating. Reading leaps to mind.